Discover Mathematics P4: Term 1, Unit 3, Lessons 1–4
GoalMeasure liquid volume in litres and millilitres, and use a conversion table to change units.
New words
litre (L) · a unit for the volume of liquids; 1 L = 1,000 mLmillilitre (mL) · a very small amount of liquid, like a few dropsconversion table · a table that lists equal amounts in two units
Explanation
Liquids such as water, juice and milk are measured in litres (L) and millilitres (mL). A bottle of water is 1 L, a small juice box is 250 mL and a spoonful of medicine is about 5 mL. The link is 1 L = 1,000 mL. A conversion table helps us change units: when the litres go up by 1, the millilitres go up by 1,000. To change litres to millilitres, multiply by 1,000. 3 L 250 mL = 3 × 1,000 + 250 = 3,250 mL. To change millilitres to litres, divide by 1,000: 4,500 mL = 4 L 500 mL. When we add or subtract, change both amounts to the same unit first, for example 1 L 500 mL + 750 mL = 1,500 mL + 750 mL = 2,250 mL = 2 L 250 mL.
Litres
Millilitres
1
1,000
2
2,000
3
3,000
5
5,000
10
10,000
Worked examples
From
To
3 L 250 mL
3,250 mL
4,500 mL
4 L 500 mL
Change 3 L 250 mL to millilitres. 3 L is 3,000 mL, and 3,000 + 250 = 3,250 mL. Change 4,500 mL to litres: 4,500 ÷ 1,000 = 4 remainder 500, so 4 L 500 mL.
Aya has 1 L 500 mL of juice and Hana has 750 mL. Together: 1,500 + 750 = 2,250 mL = 2 L 250 mL. Aya has 1,500 − 750 = 750 mL more than Hana.
A water tank holds 5 L. Marwan pours out 1 L 800 mL. The water left is 5,000 − 1,800 = 3,200 mL, which is 3 L 200 mL. Check: 3,200 + 1,800 = 5,000.
Class activity
Kitchen measures. Use a measuring jug or a 1 L bottle and a small cup. Find how many cups of water fill the 1 L bottle. Then work out how many mL one cup holds, if the bottle holds 1,000 mL. Compare with the amount printed on a juice box.
Practice
1
Change 6 L to mL.
6 × 1,000 = 6,000 mL.
2
Change 2 L 60 mL to mL.
2 × 1,000 + 60 = 2,060 mL.
3
Change 9,250 mL to L and mL.
9 L 250 mL.
4
A bottle holds 1 L. Youssef drinks 350 mL. How many mL are left?
1,000 − 350 = 650 mL.
5
Is 2 L 5 mL the same as 2,500 mL? Explain.
No. 2 L 5 mL = 2,000 + 5 = 2,005 mL. 2,500 mL is 2 L 500 mL.
